This project is designed to elucidate the early development of temporal knowledge in normal humans. It is an attempt to find the earliest ages at which humans possess temporally organized representations of unfolding events and to determine the nature of the processes underlying this ability. As part of a broader program of research by the author and other students of the developmental psychology of time, this work can help us better understand the process of cognitive development in this important domain and thereby have a detailed basis of comparison when studying pathological development. The focus in this research is on humans' sensitivity to temporal directionality in simple event sequences. Adults are highly attuned to forward vs. backward presentations of films of temporally unidirectional phenomena. However, little is known about the development of this ability or the processes underlying it. The proposed experiments will provide basic information about the ages at which sensitivity to temporal directionality appears, about the cues critical to the early perception of anomaly in reversed sequences, and about the role that learning plays in the development of temporally organized representations. Infants will be shown pairs of videotaped events, one in the vertical direction and the other in reverse. Selective looking measures will be used to determine the ages at which reliable preferences for the anomalous, backward versions appear. Further studies will investigate the importance of acceration in the detection of anomaly in gravity stimuli and whether there is an early, content general expectation that disorder will increase with the passage of time. A final experiment will test whether infants who are sensitive to temporal directionality are capable of learning novel temporal sequences. These results will shed light on the role of learning in the development of temporal representations.